My invention relates to a device for translating rotary motion into linear motion, and more specifically to such a device employing a flexible, nonstretchable band looped about a rotary member, called a pulley, for converting its bidirectional rotation into the linear reciprocating motion of another member. The rotary to linear converter in accordance with my invention has particular utility in conjunction with apparatus for the transfer of information with flexible magnetic disks, now commonly referred to as floppy disks, wherein a magnetic transducer head is linearly moved back and forth in a radial direction of the floppy disk in response to the bidirectional, incremental rotation of an electric stepping motor.
In floppy disk drives (FDDs) the bidirectional, incremental rotation of the stepping motor must be translated into the linear stepwise travel of the transducer head to enable the latter to access the individual tracks on the disk. I am aware of two prior art devices employing a flexible band or belt, as in my present invention, for such motion translation in FDDs. These are Mayeda U.S. Pat. No. 3,881,189 and Dalziel U.S. Pat. No. 4,161,004. Both patents are alike in that the opposite ends of the band are screwed to the head carriage.
I object to the screwing of the band ends to the head carriage. The band must be in exact alignment, free from torsion, for proper translation of motor revolution into linear head travel throughout the expected lifetime of the FDD. When the screws are being tightened for mounting the band of the prior art devices at the time of the assemblage of the FDD, they tend to impart torsional stresses to the band. The torsioned band will not only have a shorter useful life but also produce noise as the transducer head is transported radially of the disk in the use of the FDD. Conventionally, therefore, utmost attention and considerable time have had to be expended for mounting the band.